But packing all of those pixels into the Mini's smaller 7.9-inch display means the density jumps. So, the 324 PPI on the Mini would exceed the 264 PPI on the Retina iPad and would be just shy of the iPhone's 326.

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Of course, you really don't need a source in the supply chain to speculate about a future Retina version of the iPad Mini.

After all, the Mini is sandwiched between two marquee Apple products with Retina displays -- the iPhone 5 and iPad 4.

And one of the most consistent criticisms of the Mini is its grainy 163 pixels-per-inch display. So, Apple would be remiss if it didn't address this shortcoming at some point.

Timing of a Retina Mini is still unclear. But it may happen later rather than sooner, according to Vinita Jakhanwal, an analyst at IHS iSuppli.

Making sure there is a stable supply of a Retina-class display in the volumes that Apple demands is no easy undertaking -- especially when the Mini continues to see keen demand, even three months after its introduction on November 2.

About the author

Brooke Crothers writes about mobile computer systems, including laptops, tablets, smartphones: how they define the computing experience and the hardware that makes them tick. He has served as an editor at large at CNET News and a contributing reporter to The New York Times' Bits and Technology sections. His interest in things small began when living in Tokyo in a very small apartment for a very long time.
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